Showing 4 results for اتیلن
R. Ramezani, A. Karbassi,
Volume 6, Issue 2 (7-2002)
Abstract
In this research, sunflower oil that was extracted and refined at Shiraz Narges Oil Company was packed in four different containers, namely, clear PET (polyethylene terephtalate), yellow PET, yellow HDPE (high density polyethylene), and metal can. Samples were kept at ambient temperature in the shelf exposed to normal light for a period of 1 year. Peroxide values were determined at 45-day intervals and TBA and anisidine values were measured at 0, 6 and 12-month periods. In order to determine the effect of artificial light, some samples in PET and HDPE containers were kept in a wooden box equiped with four (20 w) fluorescent lamps and the peroxide values of the samples were determined. Light transmittance properties of the packaging materials were measured using a spectrophotometer over a wavelength range of 350 nm to 800 nm.
The data indicated that the greatest variations in peroxide, TBA and anisidine values were observed in samples in HDPE containers (significantly different at 5% level) kept under normal light and ambient temperature for a period of 1 year. It was also shown that the shelf life of sunflower oil in HDPE container was less than 6 months while for the other packaging materials it was more than one year. Samples exposed to artificial light indicated that the highest peroxide values belonged to samples in clear PET while those in yellow PET proved to have the lowest. Finally, PET container proved to be the most suitable container for sunflower oil followed by metal can. Yellow PET with the lowest transmittance percentage (350-800 nm) and peroxide value (when exposed to 20 w fluorescent lamp) could be substituted for clear PET. HDPE container proved to be unsatisfactory for sunflower oil due to high oxidation rate.
A. Kashi, S. Hosseinzadeh, M. Babalar, H. Lessani,
Volume 7, Issue 4 (1-2004)
Abstract
Watermelon (Citrullus Lanatus) cv. Charleston Gray is one of the most important cultivars grown in Iran. It has some good quantitative and qualitative characteristics but unfortunately is sensitive to Blossom End rot. To solve this problem, this experiment was conducted in a factorial manner in randomized complete block design with four replications in Research Station and Laboratories of Department of Horticulture, College of Agriculture, the University of Tehran, during 1997 & 1998. In this experiment, black polyethylene mulch was used and calcium nitrate was foliar sprayed at concentrations of 0, 4, and 6 g/L. Results indicated that mulch could increase yield by 85% over two years due to weed growth suppression and conserving soil moisture for a longer time. Foliage fresh weight, number and average weight of fruits per plant and precocity were also significantly affected by black polyethylene mulch. Furthermore, mulch reduced the number and weight of fruits affected by Blossom End rot by about 13% and 12.5% (average of two years), respectively. Calcium nitrate addition during both years had no significant effect on the measured fruit characteristics nor on Blossom End rot.
N. Meghdadian, M. Shahedi, G. H. Kabir,
Volume 8, Issue 1 (4-2004)
Abstract
Iranian flat breads generally have short shelf life. The result of this situation is usually enormous bread wastage. Among the most important factors involved are lack of proper packing and storage methods. In this study, the best temperature for bread packing was determined and the effects of three types of plastic wrapping on Taftoon bread baked of the typical flour were investigated after 72 hours of storage. These wrappings included a two-layer wrapping of oriented polypropylene and polyethylene (OPP/PE) with a thickness of 60 µ, a three-layer wrapping of PP/PE/PE with a thickness of 70 µ, and a two-layer polyethylene with a thickness of 70 µ together with cardboard and plastic. Bread packing was carried out at two different temperature ranges (20-25oC and 45-50oC). Results from moisture measurements and water activity test indicated that the characteristics of breads packed in different wrappings showed significant differences (p<0.01). Moisture percentage and water activity (aw) were lower in layers with higher permeability to moisture and water vapor and, consequently, algal growths reduced in these wrappings. Reduced moisture content, however, reduced the final bread quality score. It was also found that employing cardboard covered in polyethylene had no significant effect on bread shelf life during 72 hours of bread storage. Another finding from the present study was that packing a large number of 10×10 cm bread pieces within one single wrapping with cardboard and plastic was satisfactory and that the presence of the cardboard helped maintain bread shape during transportation and storage.
M. R. Zokaee Khosroshahi , M. Esna-Ashari,
Volume 12, Issue 45 (10-2008)
Abstract
Effect of different exogenous putrescine concentrations on post-harvest life of strawberry, apricot, peach and sweet cherry fruit was separately studied using completely randomized designs in three replicates. Fruits were immerged in putrescine solutions (0.3, 0.5, 1 and 2 mM for 5 minutes in strawberries, and 0.5, 1, 2, 3 and 4 mM for 10 minutes in the other fruits) and also in distilled water as control. They were then transferred into the fridge. Post-harvest life of all fruits was increased by the use of putrescine. Ethylene production and water loss of the fruits were reduced by this compound. Putrescine also prevented softening of fruit's tissue during their storage period. Titratable acidity was reduced in untreated fruits while their pH was increased. These trends were also observed with the application of putrescine in all fruits, but at a much slower rate compared with the controls. Soluble solids content of sweet cherry fruits was increased by the use of putrescine while it was reduced in the other three fruits.
